AC Hacking a Figidaire 5000 BTU

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Re: AC Hacking a Figidaire 5000 BTU

Postby m.colley » Sat Jun 11, 2016 10:45 pm

lrrowe wrote:Actually I was going to try a fan I have that is similar to this.
http://www.ebay.com/itm/like/3812765302 ... noapp=true

I was going to simply place it in front of my incoming vent to see if there was any improvement. Worst case is that I have to shorten the incoming tube. I will be honest and say I never considered the length/distance issue when I laid out the design.


Hey Bob,
its not the length of the added duct as much as the rise of the pipe. The fan just doesn't have the power to push it up there. In the AC business we call it static pressure loss. A typical AC system is designed to operate at a certain static pressure to achieve a certain amount of airflow rated in cfm's. Deviate from that static pressure and airflow suffers. In the Ac business there are ways to compensate for it. Its hard to do in a window a/c since its really not designed or rated to run with duct work attached to it. The fan you mentioned would help but as I said before, it"ll also change the air temp somewhat. The closer you can get the fan to the actual outlet off of your plenum/distribution box on the front of your AC the better off you'll be.

I hope this helps.

Martin
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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Sun Jun 12, 2016 6:19 am

The reasons I chose a bilge blower were that it is water proof and they can move some place around 250 CFM full bore. Ours has a PMW to control speed and it is about half speed without the coils icing up.
There have been some modifications to ours and I will post pictures the next time I use it.
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Re: AC Hacking a Figidaire 5000 BTU

Postby Socal Tom » Sun Jun 12, 2016 12:33 pm

lrrowe wrote:
capnTelescope wrote:You're forgiven, Bob. :D


Only a few months late Brad.
Here is my unit and compared to many others, it is very crude.
I installed it yesterday and with this 95 degree day here, I cannot get the Inside temp below 74.
I think I need to follow Shadow Catcher's blower idea to help move the cool air faster.
Image


Make sure you have a snug fit between the cool side and the warm side of the plenum. I reinstalled mine recently and it worked horribly, and then I discovered that I didn't have a good seal, so the cool air was just recirulating inside the plenum.
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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Sun Jun 12, 2016 12:37 pm

As I said I love seeing the variations on a theme, You do need to water proof as there is a good bit of condensation.
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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Fri Jul 22, 2016 1:05 pm

A couple of Up Dates.
I had a problem keeping the hoses stuck in the side of the trailer so last year bought two additional deck plate covers, drilled them and glued the PVC reducers in, they no longer fall out.
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The bilge blower failed (bought used on Ebay) and it was replaced.
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Re: AC Hacking a Figidaire 5000 BTU

Postby ghcoe » Wed Nov 02, 2016 8:23 am

Great article! Thanks for posting. I been thinking about how to install A/C in my build and this helps a lot.

I was thinking about the possible air flow restrictions mentioned in the tubes . What are thoughts on spring loaded or gravity actuated trap doors on the intake and exhaust sides?Could be a possible cure for some of the issues mentioned? Trap doors would open when more suction or pressure is generated in the system and bring flows back to where the plenum can work properly without excessive backpressure or suction restrictions. This would also bring in some exterior air and cut down on A/C cycling. Door pressures could be adjusted to optimize performance. Well, just a thought anyway.

Thanks again. George.
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Re: AC Hacking a Figidaire 5000 BTU

Postby capnTelescope » Wed Nov 02, 2016 9:25 am

Hey, George:

I pondered the fresh air issue, too. My solution was two fold. First, I used an uninsulated 5" dust collection hose (available from Woodcraft.com) for return air and an insulated 4" cold air flexible duct from HoDePo.

Second, I didn't get aggressive about leaks on the return air side. There's minor leakage at the couplings on both ends and I didn't try to seal off the return plenum. This lets some fresh air leak into the return. Low tech and easy.

As for the cold air, just the opposite. Seal it up as best you can. Remember that the return line is a slightly negative pressure, and the cold air line is slightly positive. You don't want to waste that precious cold air.

I don't get any freeze-ups, and the tear gets nice and cool even in Texas summer weather. Actually, the setup worked about as well without the return hose as with.

HTH. :NC
I'll burn that bridge when I come to it.

Brad
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Re: AC Hacking a Figidaire 5000 BTU

Postby capnTelescope » Wed Nov 02, 2016 9:41 am

Random thought: Inline blowers might be more effective on the trailer end of the cold air line than in the return air line. I notice that my cold air just kinda wafts into the tear's cabin.
I'll burn that bridge when I come to it.

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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Wed Nov 02, 2016 10:02 am

In my case the bilge blower on full is noisy so I used a DC DC variable voltage pulse width modulation buck converter to vary speed. The computer case fans substituting for a Fantastic Fan are on and redistributing the cool. If I had used five inch hoses as capnTelescope did I might not have needed the blower but this was proof of idea first effort. :worship:
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Re: AC Hacking a Figidaire 5000 BTU

Postby aggie79 » Wed Nov 02, 2016 3:20 pm

capnTelescope wrote:Random thought: Inline blowers might be more effective on the trailer end of the cold air line than in the return air line. I notice that my cold air just kinda wafts into the tear's cabin.


Brad,

In my (currently being replaced) PetCool setup, my cold air supply ducts are at the front of the teardrop and my return duct is at the rear of the sleeping compartment. I have a fan blower in the galley that "pushes" the return air up to the front of the teardrop. There was a considerable difference in the cold air flow with the supplemental fan blower on.

The type of fan blower I used was a centrifugal, squirrel cage blower.

Image

It is inline but is not technically an inline blower like an axial fan. Since most fan manufacturers produce pressure curve graphs and not suction curve graphs, I somewhat surmised that most fans work better in pressurization rather than suction. This was the reasoning that I placed the fan in the "pusher" arrangement.

I'm about to get back to my AC hack and am on the fence about whether or not to keep the blower fan. In the "feel test" the 5000 Btuh Frigidaire seems to have much fan higher pressure than the PetCool although both are rated at the same 120 CFM. I may just install everything and try it without the supplemental blower. If this works, I'll remove the blower.

Take care,
Tom
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Re: AC Hacking a Figidaire 5000 BTU

Postby Shadow Catcher » Wed Nov 02, 2016 3:42 pm

Tom
I tried that and ended up with coils freezing. One difference I have not discussed much is that I use the same hoses for the Espar diesel heater (they are high temp)and the blower has to be on the return line of get fried.
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Re: AC Hacking a Figidaire 5000 BTU

Postby Socal Tom » Wed Nov 02, 2016 10:16 pm

I use 5 inch OD plastic hoses intended for a portable AC unit, and I Have my inlet and outlet paralellel to the coils ( like the petcool). If I were to do it over, I'd probably use a 4 inch supply with the 5 inch return.
I believe the hose/coil arrangement helps prevent icing, since the moisture would not want to make the turn towards the coils with the momentum, and what moisture did get on the coils will me more spread accross the coils vs a 4 inch duct that focuses the moisture on a small area. Once a small area becomes iced it would easily spread over the whole coil, but if the moisture is spread out, then you are less likely to block the airflow alllowing the ice to melt when it cycles off.
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Re: AC Hacking a Figidaire 5000 BTU

Postby TallyTear » Wed Mar 22, 2017 11:13 am

Has anyone tried to upgrade the fan motor in the unit itself? I am sure it would be a pain to spec out motor that would work.


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Re: AC Hacking a Figidaire 5000 BTU

Postby working on it » Wed Mar 22, 2017 6:30 pm

  • I didn't hack my 5k unit, and don't have to regulate intake flow and return flow thru hoses. But, I did have to enlarge my exhaust ducting exit hole, and install a high-flow axial fan inside the exhaust duct to speed the hot air outside, before it stagnated, and caused thermal shutdown. Several of you are trying to get the right combination of hose sizes and if or not to install a helper fan (and what kind of fan, and where to put it). Shadow Catcher has the additional problem of also running heated air(from his heater) thru the same hoses as the cooled air.
  • I think one of the axial fans made by Aero-Flo Industries http://www.aero-flo.com/axialfans/ can be used even with heated air; mine is inside the exhaust duct from my A/C unit, and fares just fine. I bought this brand because they claim they're good up to 266 degrees F (more than my exhaust temperature, and probably more than Shadow Catcher' s heater).
  • Aero-Flo axial fans chart.PNG
    Aero-Flo axial fans chart.PNG (48.26 KiB) Viewed 712 times
  • I used the 6" model, with the lowest air flow in cfm, but it performed great, did what I needed, and I didn't have to upsize. I'm sure it would be worth installing in one of the hacked hoses, even if it was in a larger section of hose attached to a smaller one. After all, it's rated at 240 cfm, versus a Frigidaire's 120 cfm output. It could be installed in both hoses as well, since the current draw is so small. It might be worth it for you guys to try, besides, they're made in the USA.
  • axial fan pg.jpg
    axial fan pg.jpg (37.32 KiB) Viewed 712 times
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  • featuring: 3500 lb Dexter axle w/brakes & HD leaf spring system > riding on General Grabber 27x8.5-14LT tires, LED lighting inside, A/C & heat, AGM battery 12vdc, 110vac from extended run generator onboard or park power, Coleman dual-fuel stove & Northstar lantern
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Re: AC Hacking a Figidaire 5000 BTU

Postby 2manytoyz » Fri May 12, 2017 10:58 am

My question on thise fans would be at what static pressure are they producing that airflow. A 5" flex duct only carries about 50 cfm at .5 in/wc if the static rating for those fans is near that then you will potentially shorten the life of the fan considerably. I do residental and commercial hvac for anliving and a 5000 btu unit (.417 ton unit) by industry norms needs about 167 cfm. Am i missing something that is radically different with using this type of unit as I am planning a similar design for my camper.

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